Thanks for your feedback. We're sorry to heat they didn't last as long as you had hoped. Because of their size they are usually used on small metal projects and as you mentioned, intricate work, and therefore have a longer life span when used on a smaller surface area.
You may like to try using some White Aluminium Oxide Abrasive paste which is perfect for polishing soft metals:
http://www.eternaltools.com/white-aluminium-oxide-abrasive-pasteThe paste comes in a syringe, ready to use, and a small dab on a felt bob or felt mop goes a long way. If you have any other queries or need any further suggestions please contact us, we'll be happy to help.